• Progress in Medical Physics
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• v.28 no.3
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• pp.83-91
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• 2017

In this work, we investigated the recently proposed phase-contrast x-ray imaging (PCXI) technique, the so-called single grid-based PCXI, which has great simplicity and minimal requirements on the setup alignment. It allows for imaging of smaller features and variations in the examined sample than conventional attenuation-based x-ray imaging with lower x-ray dose. We performed a systematic simulation using a simulation platform developed by us to investigate the image characteristics. We also performed a preliminary PCXI experiment using an established a table-top setup to demonstrate the performance of the simulation platform. The system consists of an x-ray tube ($50kV_p$, 5 mAs), a focused-linear grid (200-lines/inch), and a flat-panel detector ($48-{\mu}m$ pixel size). According to our results, the simulated contrast of phase images was much enhanced, compared to that of the absorption images. The scattering length scale estimated for a given simulation condition was about 117 nm. It was very similar, at least qualitatively, to the experimental contrast, which demonstrates the performance of the simulation platform. We also found that the level of the phase gradient of oriented structures strongly depended on the orientation of the structure relative to that of linear grids.

• Proceedings of the Korea Information Processing Society Conference
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• 2017.04a
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• pp.661-664
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• 2017

Recently, during disasters occurrence, dealing with emergencies has been handled well by the early transmission of disaster relating notifications on social media networks (e.g., Twitter or Facebook). Intuitively, with their characteristics (e.g., real-time, mobility) and big communities whose users could be regarded as volunteers, social networks are proved to be a crucial role for disasters response. However, the amount of data transmitted during disasters is an obstacle for filtering informative messages; because the messages are diversity, large and very noise. This large volume of data could be seen as Social Big Data (SBD). In this paper, we proposed a big data platform for collecting and analyzing disasters' data from SBD. Firstly, we designed a collecting module; which could rapidly extract disasters' information from the Twitter; by big data frameworks supporting streaming data on distributed system; such as Kafka and Spark. Secondly, we developed an analyzing module which learned from SBD to distinguish the useful information from the irrelevant one. Finally, we also designed a real-time visualization on the web interface for displaying the results of analysis phase. To show the viability of our platform, we conducted experiments of the collecting and analyzing phases in 10 days for both real-time and historical tweets, which were about disasters happened in South Korea. The results prove that our big data platform could be applied to disaster information based systems, by providing a huge relevant data; which can be used for inferring affected regions and victims in disaster situations, from 21.000 collected tweets.

• Journal of the Korean Operations Research and Management Science Society
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• v.36 no.4
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• pp.43-61
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• 2011

We first develop a value ecosystem framework to model the SDP(Service Delivery Process) of web services. Since the web service has been evolving from the basic web architecture (e.g., traditional world wide web) to a prosuming platform based on virtualization technologies, the proposed framework of the value ecosystem focuses on capturing the key characteristics of SDP in each type of web services. Even though they share the basic elements such as PP(Platform Provider), CA(Customization Agency) and user group, the SDP in the traditional web services (so-called Web1.0 in this paper) is quite different from the most recent one (so-called Web2.0). In our value ecosystem, users are uniformly distributed over (0, ${\Delta}$), where ${\Delta}$��represents the variety level of users' preference on the web service level. PP and CA provide a standard level of web service(s) and prosuming service package, respectively. CA in Web1.0 presents a standard customization package($s_a$) at flat rate c, whereas PP and CA collaborate and provide customization service with a usage-based scheme. We employ a multi-stage game model to analyze and compare the SDPs in Web1.0 and Web2.0. Our findings through analysis and numerical simulations are as follows. First, the user group is consecutively segmented, and the pattern of the segmentations varies across Web1.0 and Web2.0. The standardized service level s (from PP) is higher in Web1.0, whereas the amount of information created in the value ecosystem is bigger in Web2.0. This indicates the role of CA would be increasingly critical in Web2.0: in particular, for fulfilling the needs of prosuming and service customization.

• Journal of Advanced Navigation Technology
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• v.19 no.5
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• pp.363-369
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• 2015

This paper describes deployment of a sea based sensor platform for the detection of a submarine launched ballistic missile (SLBM). Recently, North Korea successfully conducted the underwater launching test of the SLBM, which will seriously threaten the global security. To defend these threats successfully, a sensor platform of the ballistic missile defense (BMD) should be deployed in the area of high detection probability of the missile. The maximum detection range characteristics of the typical radar sensor system, however, depend on the radar cross section (RCS) and flight trajectories of the target. In this point of view, this work analyzed the flight trajectories based on the tactics and calculated the RCS of the SLBM. In addition, sea based sensor platform position is proposed from the analysis of the detection time.

• Journal of Positioning, Navigation, and Timing
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• v.9 no.3
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• pp.175-182
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• 2020

This paper introduces a study to estimate the user altitude in need of rescue in an emergency. The altitude is estimated by using the barometric pressure sensor embedded in the smartphone. Compared to GPS, which is degraded in urban or indoor environments, it has the advantage of not having spatial restrictions. With the endless development of smartphone hardware, it is possible to estimate the absolute altitude using the measured value if only the bias of the embedded barometric pressure sensor is applied. The altitude information of the person in need of rescue in an emergency is a great help in reducing rescue time. Since time is tight, we propose online calibration that provides the barometric pressure sensor bias used for altitude estimation through database. Furthermore, experiments were conducted to understand the characteristics of the barometric pressure sensor, which is greatly affected by wind. At the end, the altitude estimation performance was confirmed through an actual field tests in various floors in the building.

• Journal of Korea Game Society
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• v.8 no.4
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• pp.65-73
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• 2008

In this paper, we designed and implemented edutainment platform that can be effectively applied to developmental disabilities for their education and treatment of sensibility and intelligence training. We developed embedded hardware and contents authoring tool to make multimedia contents operated on the hardware, a management tool to provide result of training, and a real-time monitoring tool for observing the state of study. The hardware is designed by considering the characteristics of developmental disabilities and provides visual, auditory and tactile sense to assist sensibility training for their attention. User-friendly and easy-to-use authoring tool enable teachers and non-specialist to make educational contents. Also the real-time monitoring tool make us to observe user's status even in the outside of classroom. The management tool stores result of training and make us to review the result for further steps. Using this edutainment platform, efficient repetitive training is possible without restriction of time and location. Also when it applied to practical education, we can recognize that our system is effective on improving the ability of attention and studying.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.2
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• pp.73-83
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• 2011

In the manufacturing system, production-planning is very important in effective management for expensive production facilities and machineries. To enhance efficiency of Manufacturing Execution System(MES), a manufacturing system that reduces the difference between planning and execution, certain production-planning needs a dispatching rule that is properly designed for characteristic of work information and there should be a appropriate selection for the rule as well. Therefore, in this paper dispatching rule will be selected by several simulations based on characteristics of work information derived from process planning data. By constructing information that are from simulation into ontology, one of the knowledge-based-reasoning, production planning platform based on the selection of dispatching rule will be demonstrated. The platform has strength in its wider usage that is not limited to where it is applied. To demonstrate the platform, RacerPro and Prot$\acute{e}$g$\acute{e}$ are used in parts of ontology reasoning, and JAVA and FlexChart were applied for production-planning simulation.

• The Journal of the Korea Contents Association
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• v.15 no.5
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• pp.36-46
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• 2015

The purpose of this study is to investigate the characteristics of diverse contents service of EBS providing on the multi-platform in the era of smart media. This study investigated contents service of EBS in order to seek and suggest EBS's competitiveness in the era of smart media environment. As a result, EBS is providing real-time service, VOD and e-learning, but its current contents service is concentrated on providing e-learning service. This study recommended that EBS need to reinforce contents suitable for various multi-platform uses. It also suggested EBS need to cooperate with diverse webs service and SNS service in order to widen openness of its platform, and to provide not only diverse contents, but also applications by offering mobile and on-demand contents and services. Finally, this study proposed that EBS is needed to move towards a more public and comprehensive media portal.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.471-476
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• 2016

Recently, important information related with smart work such as office and video conference are handled in smart device quite a lot compare with before. Also, execution environment of smart devices is getting developed as open software environment. It brought convenience to download and use any kind of application software. By that, security side of smart devices became vulnerable. This paper will discuss characteristics of smart device security technology based on virtualization that is a mobile device platform with isolated secure execution area based on TEE (Trusted Execution Environment). Also, this paper will suggest an implementation method about safe smart device security platform based on domain separation for application software which can be executed in smart devices. The domain separation based smart device security platform technology in this paper blocks unauthorized access and leakage of sensitive information in device. Also it will be the solution can block transmission and execution of malicious code in various area including variety of IoT devices in internet rather than just smart devices.

• Journal of Ocean Engineering and Technology
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• v.19 no.5 s.66
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• pp.16-25
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• 2005

The effect of vertical riser support system on the dynamic behaviour of a classical spar platform is investigated. Spar platform generally uses buoyancy-can riser support system, but as water depth gets deeper the alternative riser support system is required due to safety and cost issues. The alternative riser support system is to hang risers off the spar platform using pneumatic cylinders rather than the buoyancy-can. The existing numerical model for hull/mooring/riser coupled dynamics analysis treats riser as an elastic rod truncated at the keel (truncated riser model), thus, in this model, the effect of riser support system can not be modeled correctly. Due to this reason, the truncated riser model tends to overestimate the spar pitch and heave motion. To evaluate more realistic global spar motion, mechanical coupling among risers, guide frames and support cylinders inside of spar moon-pool should be modeled. In the newly developed model, the risers are extended through the moon-pool by using nonlinear finite element methods with realistic boundary condition at multiple guide frames. In the simulation, the vertical tension from pneumatic cylinders is modeled by using ideal-gas equation and the vertical tension from buoyancy-cans is modeled as constant top tension. The different dynamic characteristics between buoyancy-can riser support system and pneumatic riser support system are extensively studied. The alternative riser support system tends to increase spar heave motion and needs damper system to reduce the spar heave motion.